Telephone system.



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PATENTBD Nov. 10. 1903.

AIInrne G BABCOGK. TELEPHONE SYSTEM.- APPLIOATION FILED APR. 27 .903.

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No. 743,42 1. A l Patented November 10, 1905?.

UNITED STATES PATENT O GARRISON BABCOCK, OF CHICAGO, ILLINOIS, ASSIGNOR TO STROMBERG- CARLSON TELEPHONE MANUFACTURING COMPANY, OF CHICAGO, ILLI- NOIS, A CORPORATION OF NEW YORK.

TELEPHONE SYSTEM.

SPECIFICATION forming part of Letters Patent NO, 743,421, dated November 10, 1903.

Application filed April'2'7, 1903. Serial No. 154,509. (No model.)

To all whom it may concern.- limbs, this circuit being of comparatively Be it known that I, GARRISON BABOOOK, a low resistance. The signaling instruments citizen of the United States, residing at'Chior call-bells of such bridging telephone-lines cago, in the county of Cook and State of Illiare adapted to be actuated by current from 5 nois, have invented acertain newand useful an alternating or pulsating current genera- Improvement in Telephone Systems, (Case tor located at each ofthe substations or by No. 3,) of which the following is a full, clear, a current from an alternatingcurrent gener concise, and exact description, reference beator located at the central station and whose ing had to the accompanying drawing, formterminals are adapted for connection with the to ing a part of this specification. line-limbs. As hereinbefore described, the

My invention relates to telephone systems, removal of areceiver from the switch-hook and is particularly well adapted for usein conof a substation connected with such a bridgnection with so-calledbridging telephones. ing telephone-line closes a circuit of low It is now a frequent practice to connect a resistance between the line-limbs, this low- :5 number of subscribers telephone sets each resistance circuit serving to shunt alternatv in bridge of a single telephone-line, the sub ing signaling-currents which may be imscribers call-bell or signal at each of the pressed upon the line-limbs. Thus the ringsnbstations connected with a telephone-line ing-currents pass through the telephone inbeing normally connected in bridge of the strnments rather than through the high-im- 20 two line-limbs. Such bridging telephonepedance and high-resistance call-bells. Thus bells are usually wound to a comparatively if by mistake one or more of the subscribers high resistance and impedance. The usual whose substations areconnected withabridgsubscribers telephone set includes a switching line leaves his receiver off the switch-hook hook, upon which the receiver is hung when upon having finished a conversation the t 25 not in use, this switch-hook serving under properoperationof thecall-bellsbyimpressed normal conditions to open a local-battery alternating currents is seriously interfered circuit adapted to be used for impressing telewith. A means of overcoming this defect due phonic voice-currents upon the transmissionto the accidental failure to replace a receiver line and serving at the same time to disconupon the telephone switch-hook consists in 0 nect the telephonic-receiving instruments the provision ateachsubstationofacondenser from conductive connection with the line. through which the telephone instruments are Upon the removal of the receiver from its connected with the line. Such condensers switch-hook the local-battery circuit is closed prevent the closure of a conductively-cons and the telephone instruments are connected tin nous circuit through the telephone instru- 35 in bridge of the line-limbs. The signal-bells ments upon the removal of the receiver from at the various substations connected with a its switch-hook, the continuity of the circuit telephone-line when employed in this manner being interrupted by the condenser, which is are each of comparatively high impedance, non-conductive to the passage of direct curwhereby telephonic voice-currents may be rents, but readily conductive to the passage 0 impressedupon the line-limbs and transmitof telephonic voice-currents. The said conted thereby, without being short-circuited densers, however, when connected with the through the signal-bells connected in bridge telephone-line, especially if the return-circuit of the line-limbs, for the reason that thehigh for such a line is through the ground, act as impedance of the signal-bells chokes and lightning-arresters to convey lightning dis- 45 prevents the passage of voice-currents therecharges from the metallic line to the ground,

through. The removal of a telephone-rethe passage of such a lightning discharge ceiver from its switch-hook at any one subcausing a puncture in the condenser, and station serves to close a circuit through the thereby destroying its useful purpose, as

telephone instruments between the line: above described. l

It is the purpose of my invention to provide improved circuit arrangements at each of the subscribers substations, such that a condenser may be employed without subjecting it to the danger of puncture and destruction due to lightning discharges. This result I accomplish by means of a switching device associated with the usual hook-switch, whereby a condenser is connected in circuit with the telephoneinstruments upon the removal of the receiver from the switch-hook and whereby a low-resistance circuit in shunt of the condenser is closed upon the replacement of the receiver upon the switch-hook, thereby protecting the condenser from the destructive efiect of lightning discharges.

A preferred embodiment of my invention will be made clear by reference to the accompanying drawing, in which I have illustrated a metallic line 1, between which and the ground G are connected the bridging tele erably of the well-known type in which a switch associated with the generator-armature serves to maintain the circuit normally open through the generator-armatu re, the actuation of the armature serving to cause the closure of the switch to connect the generatorterminals with the transmission-circuit.

in which the circuit Iherethrough is interrupted by the automatic switch 5. There is provided at each substation a switch-hook 6,

adapted to actuate the spring-contacts 7 and 8. I

The receiver 9 is serially connected through the secondary 10 of an induction-coil whose primary 11 is, upon the removal of the receiver '9 from the switch-hook 6, serially connected through a local circuit with the battery 12 and the transmitter 13, this circuit being traced through the contact-spring 8 and the associated spring-contact 14. The

.contact-spring 7 is provided with a front contact 15 and a back contact 16. The receiver at substation A is shown in its normal position upon the switch-hook 6, while the receiver at substation B is shown as removed tion in which the receiver 9 is upon the switch-hook 6 may be traced as follows:

At I each of the substations A and B the generat tors are illustrated in their normal condition from the binding-post 3 through the conductor 18 to call-bell 17, the conductor 19, the contact-spring 7, the contact 16, and the conductor 20 to the binding-post 4. It will thus be seen that under normal conditions the callbell 17 is connected in bridge of the telephoneline limbs. Under the same normal conditions in which the receiver is upon the switch hook the local circuit through the transmitter 13 is interrupted by the electrical disconnection of the contact 14 and the contactspring 8. Under normal conditions also the circuit through the receiver 9 and the secondary 10 of the induction-coil is interrupted by the disconnection of the spring 7 from the contact 15. Between the spring 7 and the contact 16, which is connected with the hinding-post 4, there is connected a condenser 21. It will be seen that in the normal condition of the substation apparatus the spring 7 and the contact 16 are in electrical connection, whereby the condenser 21 is short-circuited, thus protecting it from the destructive efiects of lightning discharges which might other wise take place between the line-limb 1 and the ground G through the substation apparatus.

The apparatus illustrated as located at substation B illustrates the circuit connections established upon the removal of a receiver from its switch-hook. The conductive circuit between the binding-posts 3 and 4 through the call-bell 17 is interrupted by the break in the electrical connection betweenthe spring 7 and the contact 16. The electrical connection of the spring 8 with the contact 14 closes a local battery-circuit through the transmitter 13, whereby the sound-waves impressed upon the transmitter may cause variations in the current strength through the primary 11 g of the induction-coil, thereby causing the voice-currents set up in the secondary Winding 10 to be impressed upon the line-limbs through a circuit which may be traced as follows: from the binding-post 3' through the conductor 22, the receiver 9, the secondary coil 10, the conductor 23, the contact 15, the spring 7, the condenser 21, and the conductor 20 to the binding-post 4. While the condenser 21 is opaque to the passage of direct currents, it readily permits thepassage of the rapidly-fluctuating telephonic voice-currents. It will be seen that in this abnormal position of the receiver when removed from its switchhook the condenser is connected in a circuit between the line-limb l and the ground G, where, of course, the condenser wouldbe subjected to the destructive elfects of lightning discharges; but as this condition is abnormal and should be maintained only while a subscriber is using his telephone instrument for conversational purposes the liability to destructive effects due to lightning discharges is reduced to a minimum. The replacement of the receiver upon the switch-hook upon the completion of a conversation short-cir- IlO cuits the condenser and interrupts the circuit therethrough, whereby it is at once protected that many modifications may be employed without departing from the spirit thereof. I do not therefore wish to limit myself to the precise disclosure herein set forth; but,

Haying described my invention, I claim as new and desire to secure by Letters Patent- 1. In a subscribers telephone set, the com.- bination with telephone instruments, of a condenser, and switching mechanism adapted when in one operative condition to connect serially said telephone instruments and said condenser between the limbs of atelephoneline and when in another operative condition to close a low-resistance path in shunt of said condenser. p

2. In a subscribers telephone-set, thecombination with telephone instruments, of acoudenser, and hook-switch mechanism adapted when in one operative position to connect serially said telephone instruments and said condenser between the limbsof a telephoneline and when in another alternative operative position to close a low-resistance path in shunt of said condenser.

3. In a subscribers telephone set, the combination with telephone instruments, of a condenser, and switching mechanism adapted when in one operative condition to connect serially said telephone instruments and said condenser between the limbs of a telephoneline and when in another operative condition to close a low-resistance path in shunt of said condenser and to interrupt the telephonic circuit through said telephone instruments between said line-limbs'. p

4. In a subscribers telephone set, the combination with telephone instruments, otacondenser, and hook-switch mechanism adapted when in one operative position to connect s0.- rially said telephone instruments and said condenser between the limbs of a telephoneline and when in another alternate operative position to close a low resistance path in shunt of said condenser and to interrupt the telephonic circuit through said telephone instruments between said line-limbs.-

5. In a subscribers telephone set, the combination with telephone instruments, of a condenser, and switching mechanism adapted when in one operative condition to connect serially said telephone instruments and said condenser between a telephone line and ground, and when in another alternative operative condition to close a low-resistance bination with telephone instruments, ot'a condenser, and switching mechanism adapted when in one operative condition serially to connect said telephone instruments and said condenser between a telephone line and ground and when in another alternative operative condition to close a low-resistance path in shunt of said condenser and to interru pt the telephonic circuit through said telephone instruments. 1

7. In a subscribers telephone set, the combination with telephone instruments, ot'a co'ndenser, hook switch mechanism adapted when in one operative position to connect serially said telephone instruments andsaid condenser between the limbs of a telephoneline and when in anotheroperative position to close a low-resistance path inshunt of said condenser and a local transmitter-circuit controlled by said hook-switch mechanism.

8. In combination, a telephone-line, aseries of substations adapted for bridging connection with said line, telephone instruments at each of said substations, a condenser at each of said substations, and switching mechanism adapted when in one operative condition to connect serially said telephone instruments and said condenser between the limbs of said telephone-line, and when in another operative condition to close a low-resistance path in shunt of said condenser.

9. In combination, a telephone-line, a series of substations adapted for bridging connection with said line, telephone instruments at each of said substations, a condenser at each ofsaid substations, and switching mechanism adapted when in one operative condition to connect serially said telephone instruments and said condenser between the limbs of said telephone-line and when in anotheroperative condition to close a low-resistance path in shunt of said condenser and to interrupt the circuit through said telephone instruments between said line-limbs.

10. In combination, a telephone-line, a series of substations adapted for bridging connection with said line, high-resistancesignaling-bells at each of said substations connected in bridge of the limbs of said telephone-line, telephone instruments at each of saidsubstations, a condenser at each of saidsubstations, and hook-switch mechanism adapted when in one operative position to connect serially said telephone instruments and said condenser between the limbs of said telephoneline and to interrupt the circuit through the corresponding signaling bell and when in another operative position to close a low-resistance path in shunt of said condenser.

11. In combination, a te'lephoneline, a series of substations adapted forbridging connection with said line, high-resistance signal in g-bells at each of said substations connected inbridge of the limbs of said telephone-line, telephone instruments at each of said substations, a condenser at each of saidsubsta tions, and hook-switch mechanism-adapted when in one operative position to connect serially said telephone instruments and said condenserbetween thelimbs'of said telephoneline and to interrupt the circuit through the corresponding signaling-bell and when in another operative position to close a low-resistance path in shunt of said condenser and tointerrupt the circuit through said telephone instruments between said line-limbs.

12. In combination, a telephone-line, a series of substations adapted for bridging connection with said line, high-resistance signaling-bells at each of said substations connected in bridge of the limbs of said telephoneline, telephone instruments at each of said substations, a condenser at each of said substations, and hook-switch mechanism adapted when in one operative position to connect serially said telephone instruments and said condenser between the limbs of said tele-' phone line and to interrupt the circuit through the corresponding signaling-bell and to close a transmitter-circuit through a local battery, and when in another operative posi tion to close a low-resistance path in shunt of said condenser.

13. Inasubscribers telephone set, the combination with telephone instruments comprising a receiver and an ind uction-coil winding, of a condenser, a receiver-hook adapted when relieved of the weight of said receiver to actuate switching mechanism to cause the serial connection of said telephone instruments and said condenser between the limbs of a telephone-line and adapted when the receiver is in position thereon to actuate said switching mechanism to interrupt the telephonic circuit through said telephone instruments and to close a low-resistance path in shunt of said condenser.

14. In asubscribers telephone set, the combination with telephone instruments, ofa condenser-,a receiver-hook adapted when relieved of the weight of said receiver to actuate switching mechanism to cause the serial connection of said telephone instruments and said condenser between the limbs of a tele- V close a low-resistance phone-line and adapted when the receiver is in position thereon to actuate said switching mechanism tointerrupt the telephonic circuit through said telephone instruments and to path in shunt of said condenser.

15. Inasubscribers telephone set, the combination with telephone instruments comprisbination with telephone instru ments, of a condenser,a receiver-hook adapted when relieved of the weight of said receiver to actuate switching mechanism to cause the serial connection of said telephone instruments and said condenser between the limbs of a telephone-line and adapted when the receiver is in position thereon to actuate said switching mechanism to close a low-resistance-path in shunt of said condenser.

17. Inasubscribers telephone set, the combination with telephone instruments comprising a receiver and an induction-coil'winding, of a condenser, a receiver-hook adapted when relieved of the weight of said receiver to actuate switching mechanism to cause the serial connection of said telephone instruments and said condenser between the limbs of a telephone-line and adapted when the receiver is in position thereon to actuate said switching mechanism to interrupt the telephonic circuit through said telephone instruments and to closea path in shunt of said condenser.

18. In asubscribers telephone set, the combination with telephone instruments, of a condenser,a receiver-hook adapted when relieved of the weight ofsaid receiver to actuate switching mechanism to cause the serial connection of said telephone instruments and said condenser between the limbs of a telephone-line and adapted when the receiver is in position thereon to actuate said switching mechanism to interrupt the telephonic circuit through said telephone instrument-s and to close a path in shunt of said condenser.

19. In a subscribers telephone set, the combination with telephone instruments comprising a receiver and an induction-coil winding, of a condenser, a receiver-hook adapted when relieved of the weight of said receiver to actuate switching mechanism to cause the serial connection'of said telephone instruments and said condenser between the limbs of a telephone-line and adapted when the receiver is in position thereon to actuate said switching mechanism to close a'path in shunt of said condenser.

20. In asnbscribers telephone set, the combination with telephoneinstruments, of acondenser,a receiver-hook adapted when relieved of the weight of said receiver to actuate switching mechanism to cause the serial connection of said telephone instruments and said condenser between the limbs of a telephone-line and adapted when the receiver is in position thereon to actuate said switching mechanism to close a path in shunt of said condenser.

21. In a subscribers telephone set, the combination with telephone instruments comprising a receiver and an ind uction-coil winding,

of a condenser, a receiver-hook adapted when relieved of the weight of said receiver to actuate switching mechanism to cause the serial connection of said telephone instruments and said condenser between a telephone-line and ground, and adapted when the receiver is in position thereon to actuate switching mechbination with telephone instru ments, of a condenser, and hook-switch mechanism adapted when in one position to connect serially said telephone instruments and said condenser between a telephone line and ground and when in another position to close an electrical path in shunt of said condenser.

In witness whereof I hereunto subscribe my name this 24th day of April, A. D. 1903.

GARRISON BABCOOK. Witnesses:

LYNN A. WILLIAMS, HARVEY L. HANSON. 

